In the prior art numerous keyboards are known, the term ‘keyboard’ including, besides alphanumerical keyboards, in the present context also for example PIN-pads or exclusively numerical keyboards. As a rule a keyboard has a key array formed of keys in order to provide for a user, for example, the possibility of effecting inputs to a device coupled to the keyboard, such as a communication means.
In the prior art illuminatable keyboards of this type are also known, which make it possible to effect a correct input under difficult visual conditions, for example in the dark. For this purpose such illuminatable keyboards comprise lighting means for example arranged inside the keyboard, so as to light up the key surfaces made to be partially light-transmitting, or the key array as a whole.
An illuminatable keyboard of this type, which is described in the document DE 20 2007 007 116 U1, provides lighting means in the casing such that light scattering to illuminate the key surfaces of the keyboard is achieved by means of an area that transmits light applied over a light-blocking surface, the keys themselves being arranged on a transparent printed circuit board arrangement. In this arrangement the light-transmitting zone also has, for example, light-concentrating reinforcements, in particular under the keys. This arrangement requires a considerable number of light sources in order to provide good illumination of the keyboard.